How To Convert A Photo To An Outline

[tbmow]

After getting much help from reading other peoples' posts and getting questions answered, it is time to give some back to the forum.

This tutorial describes how to take an image file and convert it into an outline suitible for printing (i.e. without using all of the ink or toner).

You can use your preferred image processing program, or, if on a PC, you can use Irfanview (a free program: http://www.irfanview.com/), which is what this tutorial uses. Each step of the tutorial describes the sequence of operations and gives the irvanview commands. A sample image is shown at the end of each step. Click on the icon to see the full-sized image. Both the keystroke and menu sequence are provided. Note: if you use a different program, you need to locate the processing commands for that specific program.

The following steps show the progress from an original image to an outline that can be used as a template. These steps are the general steps required to create an outline of an object in a picture. Different images yield different results.

1. Make a copy of your desired image and open the image in the editor. Crop it to remove extraneous items. Draw a box by dragging with the left mouse button pressed, then type <Ctrl-Y> or menu: "Edit/Crop" to crop.
   
2. Adjust the color map of the image. Do not worry if you do not see any change, this affects later operations. <Shift-U> or menu: "Image/Auto" adjust colors.
   
3. Convert the image to greyscale: <Ctrl-G> or menu: "Image/Convert to Greyscale".
   
4. Detect the edges of the picture. You may have to play with the filter setting number (1–5) depending on the image you are working with. Repeat the command using the different values and save each drawing to compare later. After a while you will get the hang of it. <Ctrl-E> or menu: "Image/Effects/Effects browser" to get a popup window of functions. Select "Edge Detect" set the filter number, and press "Apply to original image" until you get a good outline. Then press "OK" to close the popup. (Note that this produces a negative image that will be adjusted later.)
   
5. Blur the image to merge disconnected edges. <Ctrl-E> or menu: "Image/Effects/Effects browser" to get popup window. Select either of the blur options and apply it to the image. The goal is to connect any discrete dots or dashes in the outline. It is better to set a lower value and apply it a few times. This one was blurred twice using "Blur 2" with 2 iterations and 20 regluarization.
   
6. Sharpen the image to reduce the thickness of the line and remove any random dots (think static from the old TVs). This step results in a cleaner image and uses less toner or ink when printing. <Ctrl-E> or menu: "Image/Effects/Effects browser" to get the popup. Select "Unsharp mask" and set the filter to a low number. Apply it to the image a couple of times until it appears cleaned up. This image used a setting of 1 and was repeated four times.
   
7. Invert the image to create a positive image. Menu: "Image/Negative" (there are no settings).
   
8. Convert the image to black and white. This creates the equivalent of a drawing using only 2 colors. Menu: "Image/Decrease Color Depth..." to get a popup window. Select "2 colors (black/white) (1 BPP)" and click "OK" to finish.
   

This sequence used an image that started with a lot of contrast (i.e. a dark bird against a light sky). If your starting image has low contrast, crop your desired area and save it to a new file. Open the file and adjust the contrast. <Shift-G> or menu: "Image/Color corrections..." to get a popup. Play with the "Contrast" "Gamma correction" and "Saturation" settings until you see more detail brought out. Then continue with step #3 above.

Once you have your desired image, you can then scale it to the desired size before printing it.

This also has other effects (filters) available at the website.

Before anybody asks, I do not know of a similar program available on apple products. Sorry.

best

t

Note to moderators – if you need to move this to another area, please do so. This one seemed appropriate, but it could also fit in any of the others like patterns, carving, etc.

[tbmow]

Just noticed that one item was forgotten (editing is not available).

If the image does not have consistent contrast, draw a box (by holding left mouse button down and dragging) around an area. When performing the above steps, the operation works on the area within the box.

[TexasJack]

Irfranview has a lot of great features, including the ability to create an outline, and "free" is always a great price!

[Northmount]

Thanks for the tutorial. It is greatly appreciated.

Tom